1. Field of the Invention
This invention relates to a sealed rolling bearing such as a ball bearing or a roller bearing sealed by one or a pair of metallic seal rings, which comprise not only those made entirely of metal plate but those rings the marginal portion of which are to be fitted to the sealing groove which are made of metal plate, for example, a sealing ring having a sealing lip at the portion opposite to its retaining side. More particularly, this invention relates to an improved sealing ring and a sealed rolling bearing utilizing this type of sealing ring which enables maintainance of a minimum extent of deformation and dimensional change, particularly, deformation of the circularity of the outer race or inner race due to an assembly operation.
2. Prior Art
Means for retaining seal rings in sealed bearing, are known in the art. For example, U.S. Pat. No. 3,206,262 teaches each sealing ring being fixed or fitted to a sealing groove by means of a resilient seal retaining snap ring. Other prior art, such as, U.S. Pat. Nos. 2,355,805; 2,850,792 and 3,203,740, teach sealing rings being inserted directly into a sealing groove by force fitting or with further wedging. However, these prior art references have several drawbacks which it is desired to eliminate.
For example, retaining snap rings may cause only a relatively small extent of deformation and dimensional change of the bearing race due to inserting and fitting of the sealing ring, and, thus, may be more advantageous than the force fitting method with respect to dimensional accuracy. However, snap rings require a complicated configurations of the sealing groove along with preparation of extra retaining snap rings, as well as requiring improving machining and assembling efficiency, productivity, as well as in expensive production costs.
Also, there are encountered other problems with respect to the sealing performance due to variations in the sealing clearance formed, for instance, between the inner peripheral edge of the seal ring and the outer surface of the stepped portion of the inner ring. This is brought about by such inherent features of this type of fixing means that there remains only a minimum clearance necessary for assembly operation between the peripheral edge of the free side of the seal ring and the stepped surface of the inner race, and accordingly, there may arise variations in the clearance. This is liable to cause an undesirable metal to metal contact between a sealing ring and an inner race when the clearance is excessively small. Therefore, this type of fixing or fitting of the sealing ring has been found to be too difficult for application to small size bearings or miniature bearings.
On the other hand, in the latter type of fixing or fitting, both the sealing ring and the sealing groove formed in the outer or inner bearing race are of simple confirurations and their assembly can be performed by a mere force fitting or with further wedging, and therefore, is somewhat more advantageous with respect to productivity, assembling work and production costs.
However, the peripheral portion of the sealing ring is press formed and has the same thickness throughout the entire ring body. Consequently, there inevitably arises considerable deformation and dimensional change in the bearing race due to the wedging operation as well as uneven locking of the sealing ring to the sealing groove due to the deformation and/or dimensional variation. In other words, the larger the applied wedging force for preventing the uneven locking the larger is the deformation of the outer race. On the contrary, if the wedging is carried out with such a lower force that no substantial deformation is caused, there, arises another problem that the loosely wedged sealing rings may rotate during their service.
As explained above, it has been proved to be excessively difficult up to the present, to maintain deformations and dimensional change of the bearing race to be as small as possible and to firmly retain the sealing ring such that it may not rotate.
Particularly, a fatal drawback of the force type of fixing was the fact that it has been applied to almost none of the bearings having bearing races of small wall thickness, extra small bearings or miniature bearings.